When tens of thousands of African-Americans held the keys to their first homes in the early 1970s as part of a new federal program that encouraged black homeownership, they thought they were about to fulfill the American dream. Instead they got an American nightmare. The story begins with the urban uprisings of the late 1960s, which were reactions to decades of poverty, racism and a lack of opportunity. According to the Kerner Commission, a major cause was government-sponsored housing segregation that had confined African-Americans to rental housing in urban neighborhoods while subsidizing white flight to the suburbs. Black people, too,...